The Importance of Pi-Interactions in Crystal Engineering (Frontiers in Crystal Engineering) ||...

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JWST146-c12 JWST146-Tiekink January 20, 2012 14:36 Printer: Yet to come

12Supramolecular Aggregation Patternsand Stereochemical Consequences of

Tellurium(Lone Pair)···π (Aryl)Interactions

Ionel Haiduc1, Edward R.T. Tiekink2 and Julio Zukerman-Schpector3

1Department of Chemistry, Babes-Bolyai University, Cluj-Napoca, Romania2Department of Chemistry, University of Malaya, Kuala Lumpur, Malaysia

3Department of Chemistry, Federal University of Sao Carlos, Sao Carlos, Brazil

12.1 Introduction

While the formation of π -aryl bonds is typical for transition metals, the main-groupelements display a reduced tendency to form π -aryl complexes. This being stated, itwas established by the report of the so-called “Menschutkin’s complexes”, for example,C6H6.SbCl3 [1], that main-group element compounds can and do form such interactions. Inthe case of transition-metal systems, metal···π interactions are readily rationalised in termsof electron donation from the electron-rich aryl system to the electropositive metal centre.By contrast, allied interactions with main-group elements, often having a lone pair of elec-trons, seems counterintuitive. However, as indicated from macromolecular chemistry [2,3],heteroatom(lone pair)···π (aryl) interactions are stabilising. Theoretical studies indicateenergies of stabilisation ranging from 1.5 to 5.1 kJ mol−1 [4,5]. The heteroatom(lone

The Importance of Pi-Interactions in Crystal Engineering: Frontiers in Crystal Engineering, First Edition.Edited by Edward R. T. Tiekink and Julio Zukerman-Schpector.© 2012 John Wiley & Sons, Ltd. Published 2012 by John Wiley & Sons, Ltd.

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302 The Importance of Pi-Interactions in Crystal Engineering

pair)···π (aryl) interactions have been explained in terms of electron donation from themetal-based lone pair of electrons to the LUMO of the aryl ring.

In crystal engineering, it is only in recent times that metal(lone pair). . .π (aryl) interactionshave been recognised as a supramolecular synthon. The earliest systematic study evaluatedthe nature of tellurium(lone pair)···π (aryl) interactions [6] followed sometime later by asurvey of mainly light element(lone pair)···π (aryl) interactions [7]. The consequence ofsuch interactions in terms of supramolecular aggregation patterns have only been recentlysystematically evaluated for tin(II) [8] and lead(II) [9] structures. In a somewhat negativeproof of the nature of the bonding interactions arising from metal(lone pair)···π (aryl)interactions, a survey was conducted on their prevalence in situations where the arylring was substituted for an heteroaromatic ring, for example, pyridyl. Entirely consistentwith expectation, the likelihood of forming metal(lone pair) ··π (aryl) interactions fell offsignificantly [10].

In the present chapter, tellurium(lone pair)···π (aryl) interactions are again evaluatedapproximately ten years since the original survey [6] but with a focus on interactionsleading to supramolecular aggregation. Hence, self-assembly patterns are investigatedin a particular dimension in circumstances where no other competing supramolecularsynthon is operating. This is complimented by a detailed and systematic analysis of coor-dination geometries.

12.2 Methodology

The Cambridge Structural Database (CSD version 5.32, November 2010) [11] wassearched using CONQUEST (version 1.13) [12] using the structural protocols illustratedin Scheme 12.1. The two key restrictions were that the distance between the centroid ofthe aryl ring and the tellurium centre (d) be equal or less than 4.0 A, and that the angle,α, defined by the vector perpendicular to the aryl ring (V1) and the vector passing throughthe centroid to the metal atom (V2), be equal to or less than 20o. The 4.0 A cut-off waschosen based on the sum of the phenyl ring half-thickness of 1.7–1.9 A, being half thecentroid–centroid distance in parallel phenyl rings [13] and the van der Waals radii oftellurium, taken as 2.06 A, after ref. [14]. The next crucial step was the manual sorting

Scheme 12.1 Search protocols for Te(lone pair)···π(aryl) interactions: d is the distance be-tween the ring centroid of the aryl ring (Cg) and the Te atom along vector V2; V1 is thevector normal to the plane through the aryl ring; and α is the angle between the V1 and V2

vectors.

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Tellurium(Lone Pair) . . . π(Aryl) Interactions 303

of individual structures so as to exclude supramolecular architectures sustained by othersupramolecular synthons, notably secondary interactions [15], rather than tellurium(lonepair)···π (aryl) interactions. The analyses of structures were conducted with the use of PLA-TON [16] and the DIAMOND programme [17]; the latter was employed for the generationof original diagrams.

12.3 Results

Tellurium(lone pair)···π (aryl) synthons are described in the following order. Initially,neutral tellurium(IV) structures are described followed by those of neutral tellurium(II).Within each oxidation state, the structures are discussed in terms of increasing complex-ity, for example, zero-dimensional aggregates are discussed ahead of one-dimensionalaggregates. Then, structures featuring tellurium carrying a formal positive charge are sur-veyed followed by those with tellurium carrying a formal negative charge. Finally, inthe respective tables, within each category, structures are listed in order of increasingvalues of d.

12.3.1 Te(Lone Pair). . .π (Aryl) Synthons in Tellurium(IV) Structures

After manual sorting, a total of eight tellurium(IV) structures were found to exhibit Te(lonepair)···π (aryl) interactions; data are summarised in Table 12.1 and chemical diagramsof the interacting species are shown in Scheme 12.2 [18–25]. Two supramolecular ag-gregation patterns are noted in this series. Centrosymmetric dimers are found in four

Table 12.1 Te(lone pair)···π(aryl) interactions as supramolecularsynthons in tellurium(IV) compounds: selected geometric parameters(A, ◦) and supramolecular aggregation patterns

Compound [ref.] Te···Cg Te···Cg···planeSupramoleculartopology

d, (A) α, (◦)

Supramolecular dimers

1 [18] 3.41 0.92 [19] 3.51 3.03 [20] 3.57 10.94 [21] 3.74 8.5

Supramolecular chains

5 [22] 3.72 11.1 linear3.72 11.6

6 [23] 3.76 12.4 zig-zag7 [24] 3.76 19.4 zig-zag8 [25] 3.95 19.2 helical

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Scheme 12.2 Chemical diagrams for the tellurium(IV) species participating in tellurium(lonepair)···π(aryl) interactions: 1–8.

of the structures with the dimeric aggregate found in 1 [18] being illustrated in Fig-ure 12.1a. Each of 1–3 feature a single tellurium atom and each participates in a Te(lonepair)···π (aryl) interaction. However, the structure of 4 features two tellurium-containingspecies, a monomeric species Ph2TeOH(NO3), which self-associates into a dimer, and an-other, tetranuclear species, (Ph2TeO)[Ph2Te(μ-NO3)]2(Ph2TeO), which does not associatein this manner [21].

The second supramolecular motif is a chain and this is adopted by each of 5–8. Thezig-zag chain in 6 [23] is shown in Figure 12.1b being representative of the zig-zag chainin 7 and helical chain in 8. Worthy of particular mention is the linear supramolecularchain observed in 5 [22]; Figure 12.1c. Assuming the chemical composition is correct,

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(a)

(b)

(c)

Figure 12.1 Supramolecular aggregation mediated by Te(lone pair)···π(aryl) interactions intellurium(IV) structures: (a) dimeric aggregate in the structure of 1 [18]; (b) zig-zag supramolec-ular chain in 6 [23]; and (c) linear chain in 5 [22] where the nature of the individual Te···π(aryl)contacts is not fully understood, see text.

the tellurium(IV) centre has a single lone pair of electrons available for supramolecularassociation. The appearance of two putative Te(lone pair)···π (aryl) interactions indicatesthat either (i) the lone pair of electrons is equally disordered over two sites, or (ii) thetellurium atom is functioning as a donor via a Te(lone pair). . .π (aryl) interaction to onering and as an acceptor of electron density from the other ring, as observed recently in thesupramolecular chemistry of gold complexes [10,26].

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12.3.2 Te(Lone Pair). . .π (Aryl) Synthons in Tellurium(II) Structures

Examples of Te(lone pair)···π (aryl) interactions in tellurium(II) species are significantlymore numerous that for tellurium(IV) compounds, see discussion in Section 12.4. However,the supramolecular aggregation patterns of both oxidation states are similar, ranging fromdimeric aggregates to supramolecular chains; there is a sole example of a three-dimensionalarchitecture.

There are 13 examples of dimeric aggregates with data for these collated in Table 12.2[27–40]; chemical diagrams for the interacting species are given in Scheme 12.3. Basically,the dimeric aggregates fall into two classes, namely where the aggregate is sustained bya single Te(lone pair)···π (aryl) contact, that is, 9 and 10, illustrated in Figure 12.2a [28],and the remaining examples that are sustained by two Te(lone pair)···π (aryl) contacts, thatis, 11–22, usually formed between centrosymmetrically related molecules, as exemplifiedin Figure 12.2b for 13 [31]. The values of d range from 3.47 to 3.98 A cf. 3.41 to 3.74 Afound in the tellurium(IV) structures forming dimeric aggregates, Table 12.1.

An important observation in the structures is that, as seen from Scheme 12.2, many of thestructures feature more than one tellurium atom in the molecule or multiple molecules inthe asymmetric unit. Of these, in each of 9, 11, 14–18, 20 and 21, only one of the availabletellurium atoms participates in a Te(lone pair)···π (aryl) contact, whereas the others do

Table 12.2 Te(lone pair)···π(aryl) interactions as supramolecularsynthons leading to dimeric aggregates in tellurium(II) species: selectedgeometric parameters (A, ◦)

Compound [ref.] Te···Cg Te···Cg···plane

d, (A) α, (◦)

Dimeric aggregates sustained by one Te(lone pair)···π (aryl) contact

9 [26] 3.47 10.210 [28] 3.98 10.6

Dimeric aggregates sustained by two Te(lone pair)···π (aryl) contacts

11 [29] 3.55 8.112 [30] 3.67 9.513 [31] 3.68 14.414 [32] 3.70 8.215 [33] 3.74 18.2

3.79 17.916 [34] 3.76 19.017 [35] 3.79 18.418 [36] 3.81 18.619 [37] 3.82 18.920 [38] 3.87 1.921 [39] 3.87 19.022 [40] 3.94 16.4

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(a)

Scheme 12.3 Chemical diagrams for the tellurium(II) species participating in tellurium(lonepair)···π(aryl) interactions leading to dimeric aggregates: 9–22.

not. This is nicely exemplified by the structure of 16 [34] where only one of the threepossible tellurium atoms forms such an interaction; see Figure 12.2c. In this context, theexceptional structure is of 20 [38]. Here, two of the three crystallographically independenttellurium atoms associate to form a dimeric aggregate, Figure 12.2d. The third telluriumself-associates to form a flattened helical chain as detailed below. Also interesting in thestructure of 20 [38] is the observation, by contrast to the other tellurium(II) structuresdescribed thus far, that both lone pairs of electrons are involved in Te(lone pair)···π (aryl)interactions, Figure 12.2d.

Finally, a specific comment on the supramolecular structure of 14 [32] is merited. Thestructure comprises polymeric chains mediated by –Te–N–Te– bridges with three indepen-dent tellurium atoms in the asymmetric unit, only one of which forms Te(lone pair)···π (aryl)interactions. These occur between centrosymmetrically related residues resulting in the for-mation of a supramolecular layer, Figure 12.3.

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(b)

Scheme 12.3 (Continued)

With the exception of one structure, the remaining tellurium structures featuring Te(lonepair)···π (aryl) synthons, that is, 23–38 [38,41–53] adopt one-dimensional aggregation pat-terns in their crystal structures, see Table 12.3 for data. There are basically two variationsin that the majority, 11 examples, that is, 23–33, have the chains sustained by singleTe(lone pair) ··π (aryl) interactions, whereas there are five examples whereby the chains aresustained by two Te(lone pair). . .π (aryl) interactions.

The chemical diagrams of the interacting species involved in a single Te(lonepair)···π (aryl) interaction are shown in Scheme 12.4, and a representative structure isshown in Figure 12.4a for 26 [44]. The chains have various topologies ranging from linear(two examples), zig-zag (three) and helical (six). As observed above for the dimeric aggre-gates, it is often the case that within a given structure not all tellurium atoms participatein Te(lone pair)···π (aryl) interactions, for the series 23–33, structures 23–25, 28, 30 and32–33 have tellurium atoms participating in alternative intra- or intermolecular interactions.

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(a)

(b)

(d)(c)

Figure 12.2 Zero-dimensional aggregation mediated by Te(lone pair)···π(aryl) interactions intellurium(II) structures: (a) dimeric aggregate in the structure of 10 [28] mediated by a singleTe(lone pair)···π(aryl) interaction; (b) dimeric aggregate in the structure of 13 [31] mediatedby two Te(lone pair)···π(aryl) interactions; (c) dimeric aggregate in 16 [34] showing that onlyone out of a possible three tellurium atoms participate in Te(lone pair)···π(aryl) interactions;and (d) a rare example of a dimeric aggregate formed in 20 [38] sustained by two Te(lonepair)···π(aryl) interactions derived from a single tellurium atom.

There are five examples of supramolecular chains sustained by two Te(lone pair)···π (aryl)interactions, that is, 34–38, Scheme 12.5 shows chemical diagrams. A representativeexample, that is, 34 [50], is shown in Figure 12.4b. A common feature of each ofthese structures is the presence of two tellurium atoms, Scheme 12.3, and in eachstructure, with the exception of 37 [53], both tellurium atoms participate in Te(lonepair)···π (aryl) interactions. The structure of 37 [53] resembles that described above for20 [38] in that one tellurium atom utilises both lone pairs of electrons to form a pairof Te(lone pair)···π (aryl) interactions to a pair of aryl rings, Figure 12.4c. Finally, fourof the structures have linear topologies with a single example of a zig-zag topology,Table 12.3.

There is a sole example of Te(lone pair)···π (aryl) interactions leading to a three-dimensional architecture, that is, 39 [54], Scheme 12.6. Both tellurium atoms in this

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Figure 12.3 Two-dimensional array in the crystal structure of 14 [32] where chains ofmolecules sustained by –Te–N–Te– bridges are linked via Te(lone pair)···π(aryl) interactionsinvolving only one of the three possible tellurium atoms.

Table 12.3 Te(lone pair)···π(aryl) interactions as supramolecularsynthons leading to chains in tellurium(II) species: selected geometricparameters (A, ◦) and topology

Compound [ref.] Te···Cg Te···Cg···planeSupramoleculartopology

d, (A) α, (◦)

Sustained by one Te(lone pair)···π (aryl) contact per repeating unit

23 [41] 3.60 8.5 linear24 [42] 3.55 9.3 linear25 [43] 3.62 6.9 helical26 [44] 3.66 10.2 helical27 [45] 3.71 13.1 helical28 [46] 3.72 8.5 zig-zag29 [47] 3.82 14.7 helical30 [48] 3.86 12.2 helical31 [49] 3.88 9.1 zig-zag32 [48] 3.89 11.2 zig-zag33 [38] 3.92 19.4 helical

Sustained by two Te(lone pair). . .π (aryl) contacts per repeating unit

34 [50] 3.63 7.7 linear35 [51] 3.68 15.6 zig-zag36 [52] 3.69 8.6 linear37 [53] 3.71 8.0 linear38 [52] 3.80 11.4 linear

310

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(a)

(b)

Scheme 12.4 Chemical diagrams for the tellurium(II) species participating in tellurium(lonepair)···π(aryl) interactions leading to one-dimensional chains sustained by a single contact:23–33.

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(a) (b)

(c)

Figure 12.4 Supramolecular chains sustained by Te(lone pair)···π(aryl) interactions observedin the crystal structures of tellurium(II) species: (a) helical chain in 26 [44] sustained by asingle Te(lone pair)···π(aryl) interaction; (b) linear chain in 34 [50] sustained by two Te(lonepair)···π(aryl) interactions; and (c) a rare example of a linear chain formed in 37 [53] sustainedby two Te(lone pair)···π(aryl) interactions derived from a single tellurium atom.

dinuclear species participates in Te(lone pair)···π (aryl) interactions; Te···Cg = 3.67 A(Te···Cg···plane = 9.5◦) and 3.81 A (19.6◦). The resulting architecture is shown inFigure 12.5.

12.3.3 Te(Lone Pair)···π (Aryl) Synthons in Charged Tellurium Species

A total of eight cation species, that is, 40–47, were identified as having tellurium(lonepair)···π (aryl) interactions in their crystal structures in accord with the search criteria.Each of these features a tellurium(IV) centre, data are collated in Table 12.4 [55–62] andchemical diagrams are shown in Scheme 12.7.

The structure of 40 [55], Figure 12.6a, along with that of 43 [58], features interac-tions occurring between the tellurium(IV) centre in the cation with two aryl rings of thecounteranion. These represents further examples of thus-far unaccounted interactions asdescribed above for 5 [22] and 20 [38]. The supramolecular structure of 41 [56] repre-sents the sole example of a zig-zag chain, Figure 12.6b, all other examples being zero-dimensional aggregates. Analogous to 40 and 43 is the structure of 42 [57] but in which the

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Scheme 12.5 Chemical diagrams for the tellurium(II) species participating in tellurium(lonepair)···π(aryl) interactions leading to one-dimensional chains sustained by two contacts:34–38.

Scheme 12.6 Chemical diagram for the sole example of a tellurium(II) species utilising tel-lurium(lone pair)···π(aryl) interactions to generate a three-dimensional architecture: 39.

313

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(a) (b)

Figure 12.5 Three-dimensional architecture sustained by Te(lone pair)···π(aryl) interactionsobserved in the crystal structure of 39 [54]: (a) shown in projection down the c-axis; and(b) shown in projection down the b-axis.

Table 12.4 Te(lone pair)···π(aryl) interactions as supramolecular synthons in chargedtellurium compounds: selected geometric parameters (A, ◦) and supramolecularaggregation patterns

Compound [ref.] Te···Cg Te···Cg···plane Supramolecular topology

d, (A) α, (◦)

Cationic tellurium(IV) species

40 [55] 3.37 11.7 two-molecule aggregate41 [56] 3.52 6.7 zig-zag chain42 [57] 3.62 19.3 two-molecule aggregate43 [58] 3.68 17.3 two-molecule aggregate

3.73 9.644 [59] 3.69 5.7 two-molecule aggregate45 [60] 3.74 13.5 four-molecule aggregate46 [61] 3.82 8.1 two-molecule aggregate47 [62] 3.85 18.6 four-molecule aggregate

Anionic tellurium(II) species

48 [63] 3.57 7.2 two-molecule aggregate49 [64] 3.67 9.3 two-molecule aggregate50 [65] 3.93 19.1 two-molecule aggregate51 [66] 3.97 11.7 two-molecule aggregate

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Scheme 12.7 Chemical diagrams for cationic tellurium(IV) species participating in tel-lurium(lone pair)···π(aryl) interactions: 40–47. Anions/species within curly brackets are in-dicated only to show the nature of the other species in the crystal structure.

zero-dimensional aggregates is sustained by a single tellurium(IV) cation(lone pair) interac-tion with a single aryl ring of counteranion, Figure 12.6c. The zero-dimensional aggregatein each of 44 [59], Figure 12.6d, and 46 [61] arises as a consequence of the tellurium(IV)cation(lone pair) of one of the crystallographically independent cations interacting withan aryl ring of the other. The two remaining structures are four-molecule aggregates sus-tained, in part, by Te···Cl contacts. In 45 [60], two centrosymmetrically related cationsof one independent molecule associate into a dimer via mutual tellurium(IV) cation(lonepair)···π (aryl) interactions, Figure 12.6e. These, in turn, are connected on either side to thesecond independent molecule via weak Te···Cl contacts. A variation on this theme is foundin the structure of 47 [62], Figure 12.6f. Here, a cyclotetramer is sustained by alternatingtellurium(IV) cation(lone pair)···π (aryl) and Te···Cl interactions.

There are four examples only of tellurium(lone pair)···π (aryl) interactions involving an-ionic tellurium species, that is, 48–51, Scheme 12.8, and these features tellurium(II) centres,Table 12.4 [63–66]. The common feature of each is a single tellurium(lone pair)···π (aryl)interaction as exemplified in Figure 12.7a for 48 [63]. In this example, the tellurium(II)centre carries the formal charge. In the remaining three structures, there are multipletellurium centres, either neutral or charged. As anticipated on the basis of simple elec-trostatics, it is the neutral tellurium atom that forms the tellurium(lone pair)···π (aryl)interaction in each case. This principle is illustrated nicely in the structure of 50 [65],Figure 12.7b.

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(a)

(b)

(c)

(d)

(e) (f)

Figure 12.6 Supramolecular chains sustained by Te(lone pair). . .π(aryl) interactions observedin the crystal structures of cationic tellurium(IV) species: (a) zero-dimensional aggregate me-diated by the tellurium(IV) cation(lone pair) interacting with two aryl ring of the counteran-ion in 40 [55]; (b) self-association between cations leading to a zig-zag chain in 41 [56];(c) zero-dimensional aggregate mediated by the tellurium(IV) cation(lone pair) interacting

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Scheme 12.8 Chemical diagrams for cationic tellurium(IV) species participating in tel-lurium(lone pair)···π(aryl) interactions: 48–51.

(a) (b)

Figure 12.7 Te(lone pair)···π(aryl) interactions observed in the crystal structures of anionictellurium(II) species: (a) zero-dimensional aggregate mediated by the tellurium(II) anion(lonepair) interacting with an aryl ring of the countercation in 48 [63]; and (b) zero-dimensionalaggregate in 50 [65] involving the neutral tellurium(II) atom rather than the charged one.

←--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Figure 12.6 (Continued) with an aryl ring of the counteranion in 42 [57]; (d) zero-dimensionalaggregate mediated by the tellurium(IV) cation(lone pair) of one of the crystallographicallyindependent cations interacting with an aryl ring of the other in 44 [59]; (e) zero-dimensionalaggregate mediated by two tellurium(IV) cation(lone pair) interactions occurring betweenone of the crystallographically independent cations in 45 [60]. The centrosymmetric two-molecule aggregate thus formed interacts with the second independent molecules via weakTe···Cl interactions; (f) four-molecule aggregate in 47 [62] sustained by alternating tellurium(IV)cation(lone pair)···π(aryl) and Te···Cl interactions.

317

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12.4 The Influence of Te(Lone Pair)···π (Aryl) Synthons uponCoordination Geometry

By their very nature tellurium(lone pair)···π (aryl) interactions are often ignored in crystal-structure analysis, including their putative influence upon coordination environments. Inthe following, a systematic and detailed analysis of coordination geometries is undertakenwith an emphasis on determining the role of these weak tellurium(lone pair)···π (aryl)interactions upon coordination geometry, following on from a recent analysis of secondaryinteractions in tellurium 1,1-dithiolates [67].

Data summarising the different coordination geometries observed in 1–51 are collectedin Table 12.5. For the neutral tellurium(IV) structures, coordination numbers range fromsix, with coordination geometries either being distorted octahedral or distorted trapezoidalbipyramidal, to seven, that is, based on a pentagonal bipyramid. A far greater range of

Table 12.5 Coordination geometries for the tellurium compounds described herein

Coordination geometry Donor seta Compound

Neutral tellurium(IV) species

Distorted octahedral X5R 1, 2, 3, 4, 5, 7Distorted trapezoidal bipyramidal X5R 8Pentagonal bipyramidal X6R 6

Cationic tellurium(IV) species

Distorted trigonal planar X2R 41Trapezoidal pyramidal X4R 40Distorted octahedral X5R 45, 46, 47Distorted trapezoidal bipyramidal X5R 42, 44Capped trapezoidal pyramidal X5R 43

Neutral tellurium(II) species

Trapezoidal X2R2 20, 37ψ-Trapezoidal X2ER 9, 13, 16, 17, 19, 24, 27, 30, 31,

33, 35, 39ψ-Trapezoidal pyramidal X3ER 11, 14, 18, 21, 23, 25, 26, 29, 34ψ-Trigonal bipyramidal X3ER 28, 32ψ-Trapezoidal bipyramidal X4ER 10, 15, 22, 36, 38Octahedral X5R 12

Anionic tellurium(II) species

ψ-Trapezoidal X2ER 49ψ-Trigonal bipyramidal X3ER 50, 51ψ-Trapezoidal bipyramidal X4ER 48

aX = covalently bound atom or atom forming secondary interaction, E = lone pair and R = aryl ring.

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coordination geometries is observed for the cationic tellurium atoms participating in tel-lurium(lone pair)···π (aryl) interactions. This arises in part owing to interactions involvingthe counteranions. Coordination numbers range from three (distorted trigonal planar) in asingle example where one of the coordination sites is occupied by a formal Te=C bond (41),to five (one example), to the more common six. Three distinct coordination geometries aredelineated for coordination number six, that is, distorted octahedral, distorted trapezoidalbipyramidal and distorted capped trapezoidal pyramidal.

Six distinct coordination geometries are observed for tellurium(II) species engaged intellurium(lone pair)···π (aryl) interactions. Two environments give rise to four coordinategeometries, that is, TeX2R2 and TeX2ER, where X = a donor atom/group involved in acovalent interaction or a secondary interaction, E is a lone pair of electrons, and R is thearyl ring involved in the tellurium(lone pair)···π (aryl) interaction(s). Of these, 11 adopt theX2ER donor set but all structures are trapezoidal or �-trapezoidal. The next most adoptedcoordination geometry is TeX3ER, which defines a �-trapezoidal pyramidal environment;this is found in nine examples. The same X3ER donor combination also defines a �-trigonal pyramidal geometry in two examples. Two six coordinate geometries are found.Five structures have the tellurium(II) centre within a X4ER donor set, which defines a �-trapezoidal bipyramidal geometry. Finally, there is one example of a distorted octahedralgeometry based on a X5R donor set, suggesting the lone pair of electrons is sterochemicallyinert.

In the anionic species containing tellurium(II) centres, three coordination geometrieswere observed among the four structures. In the structure in which the formally negativelycharged tellurium atom is engaged in the tellurium(lone pair)···π (aryl) interaction, that is,48, the highest coordination number was found, that is, six, based on a �-trapezoidal bipyra-midal X4ER donor set. The remaining three structures had four-(TeX2ER; �-trapezoidal)and five-coordinate (TeX3ER; �-trigonal bipyramidal) coordination geometries (twoexamples).

12.5 Summary and Conclusions

The presence of intra- and intermolecular metal(lone pair)···π (aryl) interactions in thecrystal structures of tellurium compounds was established unambiguously approximatelyten years ago [6]. Herein, the impact of intermolecular tellurium(lone pair)···π (aryl) in-teractions upon supramolecular aggregation patterns has been established. Based on theseinteractions, zero- and one-dimensional supramolecular aggregates are formed, there beinga sole example of the three-dimensional architecture. Both tellurium(IV) and tellurium(II)compounds exhibit this mode of association. Rarely, tellurium(II) compounds utilise bothlone pairs to form tellurium(lone pair)···π (aryl) interactions. A curious and yet unexplainedsituation arises in several tellurium(IV) structures whereby the tellurium(IV) centre appar-ently interacts with two aryl rings.

In terms of prevalence, there are approximately 728 structures featuring both at least onetellurium atom and an aryl ring (excluding disordered, tellurium(VI) and heterometallic sys-tems). As intermolecular tellurium(lone pair)···π (aryl) interactions have been recognisedunambiguously in 51 structures herein, approximately 7% of tellurium crystal structures

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feature this mode of association. This value is marginally greater than that indicated fortin(II) [8] and lead(II) [9] structures. While low, this percentage suggests that in circum-stances where conventional intermolecular interactions are absent in a given direction, forexample, hydrogen and secondary bonding, crystal structures should be evaluated for thepossibility of tellurium(lone pair)···π (aryl) interactions.

Finally, a comment of the varied coordination numbers and even more disparate coordi-nation geometries observed in 1–51. The presence of a proximate aryl ring, held in placeby a tellurium(lone pair)···π (aryl) interaction does not confer any sense of homogeneityupon the molecular structure. The inherently weak nature of the interaction means thatits location is flexible and subject to other intra- and intermolecular bonding interactionsat play.

Acknowledgments

The Ministry of Higher Education (Malaysia) is thanked for funding crystal engi-neering studies through the High-Impact Research scheme (UM.C/HIR/MOHE/SC/03).Support from CNPq (306532/2009-3), CAPES and FAPESP (Brazil) is also gratefullyacknowledged.

References

1. D. Mootz and V. Handler, Z. Anorg. Allg. Chem., 533, 23–29 (1986).2. M. Egli and R.V. Gessner, Proc. Natl. Acad. Sci. USA, 92, 180–184 (1995).3. A. Jain, V. Ramanathan and R. Sankararamakrishnan, Protein Sci. 18, 595–605 (2009).4. M. Egli and S. Sarkhel, Acc. Chem. Res. 40, 197–205 (2007).5. B.W. Gung, Y. Zou, Z. Xu, J.C. Amicangelo, D.G. Irwin, S. Ma and H.-C. Zhou, J. Org. Chem.

73, 689–693 (2008).6. J. Zukerman-Schpector and I. Haiduc, CrystEngComm, 4, 178–193 (2002).7. T.J. Mooibroek, P. Gamez, and J. Reedijk, CrystEngComm, 10, 1501–1510 (2008).8. I. Haiduc, E.R.T. Tiekink and J. Zukerman-Schpector, in Tin Chemistry Fundamentals, Frontiers,

and Applications (2008), Chapter 3.9, 392–411 (2008). A.G. Davies, M. Gielen, K.H. Pannelland E.R.T. Tiekink (Eds) John Wiley & Sons Ltd, Chichester.

9. E.R.T. Tiekink and J. Zukerman-Schpector, Aust. J. Chem., 63, 535–543 (2010).10. E.R.T. Tiekink and J. Zukerman-Schpector, CrystEngComm, 11, 2701–2711 (2009).11. F.H. Allen, Acta Crystallogr., B58, 380–388 (2002).12. I.J. Bruno, J.C. Cole, P.R. Edgington, M. Kessler, C.F. Macrae, P. McCabe, J. Pearson and

R. Taylor, Acta Crystallogr., B58, 389–397 (2002).13. C. Janiak, J. Chem. Soc., Dalton Trans., 3885–3896 (2000).14. A. Bondi, J. Phys. Chem., 68, 441–452 (1964).15. N.W. Alcock, Adv. Inorg. Chem. Radiochem., 15, 1–58 (1972).16. A.L. Spek, Acta. Crystallogr., D65, 148–155 (2009).17. K. Brandenburg, DIAMOND. Visual Crystal Structure Information System, Version 3.1, CRYS-

TAL IMPACT, Postfach 1251, D-53002 Bonn, Germany, 2006.18. J. Zukerman-Schpector, I. Caracelli, M.J. Dabdoub, V.B. Dabdoub and M.A. Pereira, Acta

Crystallogr., C52, 2772–2774 (1996).19. A.A. Maksimenko, I.D. Sadekov, O.E. Kompan, V.I. Minkin and Yu.T. Struchkov, Khim. Get.

Soedin., SSSR (Russ.), 417–419 (1994).20. S. Sato, N. Kondo and N. Furukawa, Organometallics, 14, 5393–5298 (1995).

P1: TIX/XYZ P2: ABC



21. N.W. Alcock and W.D. Harrison, J. Chem. Soc., Dalton Trans., 1421–1428 (1982).22. S. Sato, N. Kondo and N. Furukawa, Organometallics, 13, 3393–3395 (1994).23. J. Zukerman-Schpector, I. Haiduc, M.J. Dabdoub, J.C. Biazzotto, A.L. Braga, L. Dornelles and

I. Caracelli, Z. Kristallogr., 217, 609–613 (2002).24. J. Beckmann, D. Dakternieks, A. Duthie, C. Mitchell and M. Schurmann, Aust. J. Chem., 58,

119–127 (2005).25. M.R. Sundberg, T. Laitalainen, J. Bergman, R. Uggla, J. Matikainen and S. Kaltia, Inorg. Chem.,

37, 2786–2791 (1998).26. E.R.T. Tiekink and J. Zukerman-Schpector, CrystEngComm, 11, 1176–1186 (2009).27. H. Fleischer and D. Schollmeyer, Inorg. Chem., 41, 4739–4747 (2002).28. S.C. Menon, H.B. Singh, R.P. Patel, K. Das and R.J. Butcher, Organometallics, 16, 563–571

(1997).29. F.R. Fronczek and T. Junk, Private Communication to the CSD (1996)30. P. Mallikaratchy, R.E. Norman, F.R. Fronczek and T. Junk, Acta Crystallogr., C59, o571–o574

(2003).31. J. Farran, A. Alvarez-Larena, J.F. Piniella and M.V. Capparelli, Acta Crystallogr., E65,

o812–o813 (2009).32. H. Campsteyn, L. Dupont, J. Lamotte-Brasseur and M. Vermeire, J. Heterocycl. Chem., 15,

745–748 (1978).33. P.G. Jones and J. Jeske, Private Communication to the CSD (2004).34. M.D. Milton, N. Kumar, S.S. Sokhi, S. Singh and J.D. Singh, Tetrahedron Lett., 45, 6453–6455

(2004).35. S.K. Tripathi, U. Patel, D. Roy, R.B. Sunoj, H.B. Singh, G. Wolmershauser and R.J. Butcher,

J. Org. Chem., 70, 9237–9247 (2005).36. G. Mugesh, A. Panda, S. Kumar, S.D. Apte, H.B. Singh and R.J. Butcher, Organometallics, 21,

884–892 (2002).37. J. Zukerman-Schpector, I. Caracelli, M.J. Dabdoub and V.B. Dabdoub, J. Chem. Crystallogr.,

26, 389–392 (1996).38. L. Engman, I. Kania, B.J. Oleksyn, J. Sliwinski and A. Wojton, J. Mol. Struct., 609, 47–54

(2002).39. E.A. Meyers, R.A. Zingaro and N.L.M. Dereu, Z. Kristallogr., 209, 992–992 (1994).40. T.A. Hamor, A.G. Maslakov and W.R. McWhinnie, Acta Crystallogr., C51, 2062–2064

(1995).41. G. Llabres, O. Dideberg and L. Dupont, Acta Crystallogr., B28, 2438–2444 (1972).42. A.L. Fuller, L.A.S. Scott-Hayward, Y. Li, M. Buhl, A.M.Z. Slawin and J.D. Woollins, J. Am.

Chem. Soc., 132, 5799–5802 (2010).43. D.J. Sandman, L. Li, S. Tripathy, J.C. Stark, L.A. Acampora and B.M. Foxman, Organometallics,

13, 348–353 (1994).44. L. Engman, A. Wojton, B.J. Oleksyn and J. Sliwinski, Phosphorus, Sulfur, Silicon, Relat. Elem.,

179, 285–292 (2004).45. T.M. Klapotke, B. Krumm, H. Noth, J.C. Galvez-Ruiz, K. Polborn, I. Schwab and M. Suter,

Inorg. Chem., 44, 5254–5265 (2005).46. H. Sashida, M. Kaname, A. Nakayama, H. Suzuki and M. Minoura, Tetrahedron, 66, 5149–5157

(2010).47. A.G. Maslakov, W.R. McWhinnie, M.C. Perry, N. Shaikh, S.L.W. McWhinnie and T.A. Hamor,

J. Chem. Soc., Dalton Trans., 619–624 (1993).48. J. Farran, L. Torres-Castellanos, A. Alvarez-Larena, J.F. Piniella and M.V. Capparelli, J.

Organomet. Chem., 654, 91–99 (2002).49. J. Farran, A. Alvarez-Larena, J.F. Piniella, M.V. Capparelli and L. Torres-Castellanos, Acta

Crystallogr., C53, 342–343 (1997).50. G. Le Guillanton, A.V. Martynov, J. Delaunay, N. Mercier and A. Riou, J. Chem. Res. (S),

681–681 (1998).51. E. Schulz Lang, R.A. Burrow and E.T. Silveira, Acta Crystallogr., 58, o397–o398 (2002).52. S.C. Menon, H.B. Singh, R.P. Patel and S.K. Kulshreshtha, J. Chem. Soc., Dalton Trans.,

1203–1207 (1996).

P1: TIX/XYZ P2: ABC



53. T.M. Klapotke, B. Krumm, P. Mayer, H. Piotrowski and K. Polborn, J. Fluorine Chem., 123,133–138 (2003).

54. G. Van den Bossche, M.R. Spirlet, O. Dideberg and L. Dupont, Acta Crystallogr., C40, 1011–1012(1984).

55. Z.-L. Zhou, Y.-Z. Huang, Y. Tang, Z.-H. Chen, L.-P. Shi, X.-L. Jin and Q.-C. Yang,Organometallics, 13, 1575–1581 (1994).

56. M.R. Detty, J.M. McKelvey and H.R. Luss, Organometallics, 7, 1131–1147 (1988).57. R.H. Jones and T.A. Hamor, J. Organomet. Chem., 269, 11–20 (1984).58. Z.-Z. Huang, S. Ye, W. Xia, Y.-H. Yu and Y. Tang, J. Org. Chem., 67, 3096–3103 (2002).59. T.M. Klapotke, B. Krumm, P. Mayer, H. Piotrowski, I. Schwab and M. Vogt, Eur. J. Inorg. Chem.,

2701–2709 (2002).60. R.F. Ziolo and M. Extine, Inorg. Chem., 19, 2964–2967 (1980).61. D.D. Titus, J.-S. Lee and R.F. Ziolo, J. Organomet. Chem., 120, 381–388 (1976).62. M.J. Collins, J.A. Ripmeester and J.F. Sawyer, J. Am. Chem. Soc., 110, 8583–8590 (1988).63. K. Maartmann-Moe and J. Songstad, Acta Chem. Scand. A, 36, 829–839 (1982).64. H. Wolkers, B. Schreiner, R. Staffel, U. Muller and K. Dehnicke, Z. Naturforsch., B: Chem. Sci.,

46, 1015–1019 (1991).65. H.T.M. Fischer, D. Naumann and W. Tyrra, Z. Anorg. Allg. Chem., 633, 127–131 (2007).66. H.T.M. Fischer, D. Naumann and W. Tyrra, Chem. Eur. J., 12, 2515–2519 (2006).67. E.R.T. Tiekink and J. Zukerman-Schpector, Coord. Chem. Rev., 254, 46–76 (2010).

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